( I ©7 1 ) ^ 
'the Leaves a fort of dark and faded Green, variegatcii^ 
See Tab. 7. fig. l. The Crjjial with other Natural Curio" 
fities, was given n:ie by the Learned and In^mlom Dr Ja- 
kz Cay of Newcaftle^ who brought it from Milan : And 
becaufe his defcription will be much more accurate than I 
can pretend to, I will make bold therewith, . m\y pre* 
mifing his arguments upon a fort of Spar within a Flinty 
Tent me at the fame time. That within the Flint f fays 
he) feems to diflfer from the reft of its fubftance, and 
fbmewhat to refemble Spar : Tho after all, Spar being 
nothing elfe-but a Crifialline fort of Lime-Jione^ it differs 
not from Fli^t in reality, but only in appearance, i.e. in 
. the manner of Concretion, tho if the inclofed Matter bad 
in its nature differ d from the reft of the Stone, the thin*g 
had not been very uncommon, it being ufual enough for 
Stones (efpecially thofe of a globular or oval form ) te 
have Goat upon Goat, and thofe Coats fometimes very 
different one from another, feme of them foft, fomehard^ 
nay, fometimes after a long fpace of time, one of thefe 
Coats will ftirink from another, after the manner of a 
Kernel when the Shell grows dry ^ and then it the en- 
clofed fubftance continue foft and marly, they call that 
Stonc GWe/^ but if ftony, it make's one of thofe Rattling 
Stones that are known by the name ot the Mtites^ or Ea- 
gle Stone. To confirm Vv^hat I have here advanced, rt 
were eafie to prove by many Inftances that it is no unufu*- 
al thing for Scones to enclofe* Subftances of a very differ- 
ing nature from themfelves ^ the Shells in the Suffix Mar- 
He herewith fent you is one proof of this matter, and the 
Stones found in our Coal pits, and known amongft the 
Workmen by the name of Cat-heads, may ferve tor ano- 
ther 5 they are fougd in a particular Stratum near the 
Goal, and enclofe a Fern, or fometimes Polypody Leaf in, 
the middle of them 5 and. for that reafon being ftrucji 
with a Hammer very readily break there: I think they 
'-are a fort of ir<?;? Stone^ ' 21km ta that which they call in 
Fffffff ' Staf^ 
